As the technology progresses rapidly, the multi-media computer system is now widely available at an affordable price to most users. Conventional multi-media computer systems are usually designed to accommodate add-on audio video functional modules, so that existing systems can be upgraded. Hence, the synchronization of many data and control buses plays an important role in determining the performance of the multi-media computer system.
FIG. 1 shows a conventional two-bus system, including a CPU/Sound/Graphic unit 11, a program and sound memory 12, a graphic memory 13, a TV/LCD signal unit 14, a program and sound bus 15, and a graphic bus 16. CPU/Sound/Graphic unit 11 communicates with program and sound memory 12 through program and sound bus 15, while with graphic memory 13 through graphic memory 16. After processing, the displayed data are then sent to TV/LCD signal unit 14, and separated into video output, and audio outputs.
Conventional structure of two-bus multi-media computer systems has several shortcomings due to having two buses. As the CPU/Sound/Graphic unit 11 can only communicate with a memory at one time, the two buses must be synchronized in communicating with CPU/Sound/Graphic unit 11. The synchronization adds extra overhead to CPU/Sound Graphic unit 11 and wastes precious processing cycles. Further more, the circuit complexity of CPU/Sound/Graphic unit 11 increases because it also needs extra circuit to perform the synchronization.